Patent GB-735586-A (GB)
Title: Improvements in or relating to an electrically operated data reproducing and recording system
IPC: G09G1/18
Filed: 1952-12-10
Abstract: 735,586. Viewing by scanning. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 10, 1952 [Dec. 24, 1951], No. 31276/52. Class 40 (3). An arrangement for reproducing data, e.g. letters and numerals, comprises a first cathode. ray tube in which the characters are formed on a mask secured to or adjacent the fluorescent screen of the tube which is scanned over an area corresponding to the desired character to produce in conjunction with a photo-cell the corresponding signals which are applied to a second cathode ray tube having its area-scanning movements synchronized with those of the first cathode ray tube and additionally controlled so that the characters scanned are reproduced in a sequential order on the screen of the second tube. The Y-sweep circuit together with control circuits for selecting the character and for the sequential positioning of the reproduced characters are under control of a timing circuit 20 comprising a ring of nine trigger devices T1 ... T9, Fig. 2a, and an auxiliary trigger T10 controlled by pulses from an amplifier 19, wave-shaping circuit 18 and multivibrator 17 comprising valves V1, V2 cross connected and frequency controlled by the elements 53, 58 and 54, 62. The valve V4 of the shaping arrangement is conductive when V2 is non- conductive and V3 is conductive solely when the valve V4 is non-conductive and square pulses appearing at the anode 102 of valve V3 are applied to the grid 103 of the valve V5. These pulses, which are taken from resistor 79 in the anode circuit V5 and which are inverted relative to the applied pulses, are fed to the grid 105 of the left-hand valve V6 of the trigger T1 which is normally conducting so that the trigger is shifted to the " off " condition. The trigger devices T1 ... T9 (Fig. 2a) form a closed ring and the trigger device T1 being rendered "off" for each ninth pulse applies a pulse to corresponding trigger devices T11 ... T17 of a ring 24 and triggers T18 ... T24 forming a ring 23, which are associated with power devices P1 ... P7 and P8 ... P14 respectively. The output of a power device P1 ... P7, Fig. 2b, whilst the corresponding trigger T11 ... T17 is in the " on " condition is connected through a resistor 135 and a series potentiometer, 136, the tapping point of which is fed to a terminal 139 connected to the Y-scan generator 27 of the tube 12. Whilst the trigger T11 is " on," i.e. the valve V9 conducting, the valve V11 passes current and the potential applied to the screen grid 134 is adjusted at potentiometer 131 so that the voltage applied to the terminal 139 selects the Y co-ordinate of the character to be scanned. At the same time the " on " operating condition of the corresponding trigger of the set T18 ... T24 causes the corresponding valve of the power unit P8 . . . P14 to pass current of value determined by its screen grid potential so that the voltage at terminal 143 from potentiometer 141 in series with resistor 142 and applied to generator 28 selects the X co-ordinate of the character to be scanned. In a similar manner, the pulses from the first trigger of the ring T1 . . . T9 sequentially operate a ring 22 of seven triggers and scanning generator 30 to cause the scanning beam to reproduce the characters in sequential order, and after the completion of a line of characters a pulse produced by the first trigger of the ring 22 operates over circuit 25 a three-trigger ring 26 to produce a voltage which is applied via terminal 164 to the Y-scan generator 29 so that a line of characters is reproduced in triplicate, i.e. three identical or repeated lines of characters. A gating circuit 42 controlled by the trigger T10 which is switched " on by the trigger T3 and " off " by the " off " condition of trigger T9 applies a blanking voltage to the control grid of the tube 12 and to the sweep circuit 32 when in its " off condition. The signal pulses derived from the photo-cell PT by the scanning of the screen 37 are pased by a cathode follower 39 and amplifier 40 to a clipper 41 operating so that the beam of that cathoderay tube 14 is " on for the period that the tube PT is energized. Specification 673,769, [Group XIX], is referred to.